In an aircraft, for example, a number of seats are continuously provided in a longitudinal direction to arrange a predetermined number of seats in a limited space. The seating space of each passenger is thus limited to be a predetermined size. In particular, there has been a problem that, when a passenger in a front seat reclines a seat backward to take a resting posture, the leg room (footrest) space of a passenger in a rear seat is significantly limited and this causes deterioration in comfort. In view of this problem, regarding such an aircraft, an effort has been required to maintain a wider seating space including the leg room (footrest) space between the front seat and the rear seat to improve passengers' comfort.